Back-side illumination solid state imaging devices are known for, because of an interconnection layer being formed on the opposite side to a light receiving surface, being capable of reducing the height of the light collection structure and being capable of achieving good oblique incident light characteristics, as compared to front-side illumination solid state imaging devices.
There is known a solid state imaging device in which phase difference detecting pixels in which part of a photoelectric conversion unit is shielded from light are provided among ordinary imaging pixels and thereby phase difference detection is performed. In the phase difference detecting pixel, it is necessary to increase the distance between a microlens and a light blocking film in order to bring the light collection point onto the light blocking film, that is, to increase the height of the light collection structure.
Here, in the case where a phase difference detecting pixel is provided in a back-side illumination solid state imaging device, a trade-off occurs in which height reduction is required in order to obtain oblique incident light characteristics of the imaging pixel and at the same time height increase is required in order to obtain AF characteristics of the phase difference detecting pixel.
To solve the trade-off, an imaging element is proposed in which, while the height of the microlens is equalized between the imaging pixel and the phase difference detecting pixel, the light receiving element of the phase difference detecting pixel is formed low (see Patent Literature 1). Furthermore, it is disclosed that the imaging distance of the phase difference detecting pixel is ensured by providing a level difference for the microlens of the phase difference detecting pixel (see Patent Literature 2).